1. Field of the Invention
The present invention relates to a liquid crystal display device, more specifically, the present invention relates to a ferroelectric liquid crystal display device, an antiferroelectric liquid crystal display device and an in-plane switching-mode liquid crystal display device where the display is effected by applying a transverse electric field to a nematic liquid crystal aligned in the horizontal direction.
2. Description of the Related Art
As for the liquid crystal display device, a system of interposing a liquid crystal layer comprising a nematic liquid crystal oriented in the twisted alignment between two orthogonal polarizing plates and applying a vertical electric field to the substrate, namely, a so-called TN-mode, is being widely used. In this system, since the liquid crystal stands up with respect to the substrate at the black display, birefringence is generated due to liquid crystal molecules when the screen is viewed from the oblique side, and light leakage occurs. In order to solve this problem, a system of optically compensating the liquid crystal cell by using a film where liquid crystalline molecules are oriented in the hybrid alignment, thereby preventing the light leakage, is being used in practice. However, it is very difficult to optically compensate the liquid crystal cell completely without problem even by using liquid crystal molecules, and there is a problem that gradation reversal cannot be prevented in the down direction of the screen.
For solving such a problem, a so-called in-plane switching (IPS)-mode liquid crystal display device where a transverse electric field is applied to the liquid crystal, or a vertically aligned (VA)-mode liquid crystal display device where a liquid crystal having a negative dielectric anisotropy is vertically aligned and the alignment is divided by a protrusion formed in the panel or a slit electrode, has been proposed and put into practical use. In recent years, development of such a panel is proceeding not only for the monitor use but also for the TV use, and along with this development, the brightness of screen is greatly enhanced. As a result, slight light leakage in the obliquely incident direction with respect to the diagonal position at the black display time, which has been heretofore not a problem in these operation modes, comes to appear as a cause of the reduction in the display grade.
As means for improving the color tone or the viewing angle at the black display time, studies are being made also in the IPS mode to dispose an optical compensation material having birefringence property between the liquid crystal layer and the polarizing plate (see, for example, JP-A-10-307291).
On the other hand, in these liquid crystal display devices, an antiglare film is disposed on the outermost surface of the display to prevent projection of an image due to reflection of outside light, thereby attaching a high added value to the liquid crystal display.
As for the antiglare film, an antiglare film having internal scattering property in addition to surface scattering is known (see, for example, Japanese Patent No. 3,515,401).
In the case of applying an antiglare film to an IPS-mode liquid crystal display device, it has been found from studies by the present inventors that even when optical compensation is made in the liquid crystal display device, if an antiglare film having an insufficient effect of preventing projection of an image due to reflection of outside light is applied, a problem such as reduction in the dark room contrast arises.